exceptions can be found, I believe that most species can be identified from the 

 pigmentation pattern, in combination with other obvious external features and 

 additional criteria (e.g., shape of the tail, geographic location, etc.). . . 



Phylogenetic relationships of fishes can be notoriously difficult to evaluate on 

 the basis of pigmentation, due to difficulties in coding color patterns and 

 determining polarities, tranformation sequences, and homoplasies. For these 

 reasons, I have avoided using pigmentation to infer possible relationships among 

 ageneiosids. Certain patterns may represent shared derived conditions, such as 

 strong mottling and the presence of one or two large crescentic spots in the tail 

 (most intense in A. vittatus, present to a lesser degree mA.pardalis,A. ucayalensis, 

 and^. valendennesi). However, in the absence of clearly defined patterns in 

 outgroups, one is unable to determine whether in fact such patterns are derived or 

 not. In many cases, generaUzed pigmentation patterns are common in other 

 neotropical fishes, thus indicating convergence that has probably resulted from 

 selection based on ecological factors. For instance, many doradids, some 

 auchenipterids, and a number of umelated catfishes and characins have prominent 

 spots or stripes in the caudal fin; such disruptive coloration, perhaps functioning to 

 confuse predators, has undoubtedly evolved independently in many unrelated 

 lineages of fishes. 



Neurocranium • ; ■ • v ;■ " ■: 



Few previous studies have presented detailed accounts or illustrations of the 

 ageneiosid cranium. Regan (1911) briefly characterized the skull of all doradoids 

 (as his family Doradidae), many of the salient features of which are found in 

 ageneiosids. His distinction of the doradoid neurocranium included the following: 



palatine rod-like; pterygoid absent; mesopterygoid connecting the metapterygoid 



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